Fuse device



Oct. 12; 1943 E. A. LINK FUSE DEVICE Filed June 27, 1942 5 Sheets-Sheet l INVENTOR. BY Zak/MA [/M E A. LINK FUSE DEVICE Oct. 12, 1943.

Filed Jime 27, 1942 s Sheets-Sheet 2 III P INVENTOR. [mm/,4. [/A/A/ Oct. 12, 1943.

E. A. LINK 2,331,839

FUSE DEVIG Patented Oct. 12, 1943 UNITED STAT s PAEN OFFICE to Line Materiai Company,

South Milwaukee,

a corporation of Delaware Application June 27, 1942, Serial Nor cameo 22 Claims.

This invention relates to fuse devices.

Objects of this invention are to provide a fuse device which employs a fuse tube open at both ends and which has a headed fuse link so ar ranged that the head of the fuse link closes one end of the fuse tube, and in which the head of the fuse link is adapted to be blown directly away from the end of the fuse tube in the event of a violent evolution of gas upon rupture of the fuse link so that the fuse tube will be vented at both ends.

Further objects are to provide an expulsion fuse device in which a fuse tube is provided which is open at both ends and in which a fuse link is positioned within the fuse tube and is provided with a head normally closing one end of the fuse tube, and in which stationary contacts are electrically connected under normal conditions by means of the fuse link, and in which provision is made for the free travel of the head of the fuse link away from the end of the fuse tube without engaging the adjacent stationary contact so that even under violent overload conditlons no damage will be caused the stationary contact by the violent projection of the head of the fuse link outwardly away from the end of the fuse tube, and to provide a construction having the characteristics enumerated above in which the head of the fuse link has good and positive electrical contact with the adjacent electrically conducting portion of the fuse device.

A further specific object of this invention is to provide an expulsion fuse device in which the fuse tube is open at both ends, one end being closed by the head ofthe fuse link and the head of the fuse link being gripped in such a manner that under light overloads the head of the fuse link will not be blown off and the action of the fuse tube will be that of a fuse tube open at one end only to thereby assist in the speedy clearing of the circuit inside the fuse tube, the construction being such that under heavy overloads the head of the fuse link is blown from the fuse tube tothereby provide venting of the fuse tube at both ends, the device therefore having both the characteristics of an expulsion fuse tube open at one end only for light overloads and vented at both ends for heavy overloads, whereby the safe rupturing capacity of the apparatus is materially increased.

' In greater detail, further objects of this invention are to provide a fuse construction in which a nut is screwed on one of theiopen ends of the fuse tube and is provided with an aperture therethrough having a slanting inner surface which may be smooth or which may be provided with serrations and which engages the marginal edges of the button head or other shaped head of the fuse link and causes such head to bind tightly against the end of the fuse tube under normal conditions and thus secures excellent electrical contact between the head of the fuse link and the end, terminal of the fuse tube as well as with the nut itself, the head of the fuse link being sumciently soft to permit the head to be slightly deformed and pass outwardly from the nut when sufficient gas pressure is generated within the fuse tube under violent overload conditions.

Further objects are to provide a, construction in which the nut may be readily renewed at a minimum of expense in the event the nut becomes corroded or severely burned.

Further objects for another form of the invention are to provide a construction in which the upper terminal of the fuse tube is recessed and receives the head of the fuse link and is provided with a set screw for clamping the head of the fuse link in place, the head of the fuse link being sufliciently soft sothat it will yield and will be blown outwardly from the upper terminal of the fuse tube when sufficient gas pressure is generated within the fuse tube upon heavy overload.

Further objects are to provide a construction in which the head of the fuse link and the nut or other gripping member for the head of the fuse link are located above the adjacent portion of the stationary contact so that upon violent overload the head of the fuse link will be projected from, and the blast of gases will occur at a point above the stationary contact, thereby avoiding damage to the stationary contact, the fuse tube being so arranged that it will drop outwardly from operative to inoperative position after the circuit has been interrupted within the fuse tube.

Embodiments of the invention are shown in the accompanying drawings, in which:

Figure 1 is a side elevation showing the device in operative position.

, Figure 2 is a sectional view on the line 2-4 of Figure 1.

Figure 3 is a sectional view on the line 3-4 of Figure 1.

Figure 4 is a view of the fuse tube removed from the remainder of the apparatus, such view being partly broken away and partly in section.

Figure 5 is a view looking down on the upper end of the structure shown in Figure 4.

'an arm rigid with the fuse tube Figure 6 is a view corresponding to Figure 4 showing a further form of the invention.

Figure 7 is a view corresponding to Figure 4 showing a further form of the invention.

Figure 8 is a view looking down on the upper end of Figure '7.

Figure 9 is a view corresponding to Figure 8 showing a still further form of the invention.

Referring to the drawings, particularly Figures 1 to 5, it will be seen that the device comprises a pair of stationary contacts which may be carried by a suitable elongated insulator I, such insulator itself being supported in any suitable manner. The lower contact may comprise a pair of spaced hook like members 2 which are adapted to receive the trunnions 3 of a lever 4 pivotally mounted between the bifurcated ends of 8. The lever [is provided with a web portion 1 which may terminate in a hook portion 8 for the reception of a switch stick for replacing the fuse device after it has been refused. The web 1 extends outwardly from the trunnions 3 and prevents inadvertent detachment of the trunnions 3 from the hooks 2 until the fuse tube has rocked downward to its lowest position. Preferably a pair of annular flanges 9 are carried by the web 1 to assist in correctly positioning the trunnions within the hooks 2 when the device is being replaced by means of a switch stick.

The lever 4 is provided with a thumb nut ill by means of which the leader ll of the fuse link is clamped. Normally the parts are in the position shown in Figure 1. Upon rupture of the fuse link the lever 4 rocks downwardly and thus lowers the fuse tube and allows it to detach itself from the upper stationary contact hereinafter described so that the fuse tube will drop outwardly and downwardly out of operative position after the circuit has been cleared within the fuse tube.

The upper end of with an upper terminal member i2 the fuse tube is provided which is equipped with a pair of outwardly projecting contact pins I3. The contact pins are adapted to engage beneath a pair of spring arms 14 forming a part of the upper stationary contact. These spring arms are provided with downwardly depressed portions l5 behind which the pins 13 are yieldingly hooked when the device is rocked into operative position, as shown in Figure 1. These arms l4 preferably diverge at their outerends, as shown most clearly in Figure 2, and slant upwardly, as shown in Figure 1, so as to allow the pins i3 to ride beneath the arms into locking position, as shown in Figure 1, when the fuse tube is rocked upwardly into position. The upper terminal i2 of the fuse tube is provided with an eyelet portiom i6 adapted to be engaged by a switch stick when the fuse tube is rocked into operative position or when the fuse tube is rocked out of operative position.

The arms 14 may be formed of resilient heavy spring wire and are preferably provided with coiled portions l'l adjacent their rear ends to increase the resiliency of the arms. The arms are preferably roughly U-shaped, as shown in Figure 2, and the rear portion I8 of such arms is clamped in place between the line receiving portion IQ of the upper terminal and the rear portion of a bracket 20. A convenient way of clamping the members in place is by means of a screw 2| which passes through the upper end of the insulator and may be threaded into the base of the bracket 20.

'The bracket 20 extends outwardly, as shown in Figures 1 and 2, and is provided with an outer transverse portion or plate 22 which acts as a stop to limit the inward rocking motion of the fuse tube when the device is being rocked into operative position. This plate 22 is provided with upwardly opening slots 23 on opposite sides thereof within which slots the spring arms I! are freely received. This construction prevents spreading of the spring arms and insures their correct positioning.

The fuse tube is open at both ends. At its upperend it opens through the terminal l2 and such terminal is provided with a reduced neck portion 24 whose lower portion is threaded as indicated at 25. .A nut 26 is screwed on the reduced neck portion and is provided with an aperture therethrough which has a slanting inner surface 21. When the nut is screwed downwardly, it binds against or grips the side edges of the button head 28 of the fuse link, such fuse link being provided with a reduced fusible seciton 29 and the flexible leader ii and extending through the fuse tube and out from the open end thereof. The downward screwing of the nut 28 forces the head of the fuse link tightly against the upper face of the reduced neck 24 of the upper terminal l2 of the fuse tube and thus secures a firm electrical contact between the head of the fuse link and the upper terminal, in addition to the contact provided by the frictional engagement of the inner surface 21 with the marginal edges of the head 28 of the fuse link.

It is to be noted that the fuse tube is normally closed at its upper end by the head of the fuse link and under light overloads it operates as a straight expulsion fuse, the upper end remaining closed. Under heavy overloads the fuse tube is vented at its upper end as well as at its lower end and the head of the fuse link, which is made of soft material, is distorted and blown outwardly through the nut 26 and away from the upper end of the fuse tube.

In this way the device is capable of handling large overloads without danger of bursting the fuse tube as provision has been made for the free venting of the fuse tube at both ends under heavy v overloads. The fuse tube can, therefore, handle larger overloads than one in which the upper end remains permanently closed.

Another point to be noted is that the head of the fuse link is projected upwardly from a point above the upper stationary contact and consequently there is no chance of damage to the upper stationary contact as no portion thereof is struck by the outwardly projected head of the fuse link nor is any part burned by the outward blast of gases.

Instead of having a separate nut as shown in the first form of the invention and described hereinabove, the fuse tube 29, see Figure 6, may be provided with an upper terminal member 30 which opens into the bore of the tube. The aperture through the terminal 30 may be a twobore aperture, the larger bore being indicated at 3| and the smaller bore at 32. The larger bore provides, with the smaller bore, a shouldered portion 33 on which the button head 34 of the fuse link rests. A set screw 35 is threaded transversely through the terminal 30 of the fuse tube and engages the edge of the head of the fuse link and forces the head into engagement with the wall on the opposite side of the larger opening 3|, thus securing the head in place. However, the head of the fuse link, as stated, is formed of soft material and deforms when sufficiently high gas pressure is generated within the fuse tube upon heavy overloads and is blown outwardly away from the terminal of the fuse tube. The terminal of the fuse tube is constructed otherwise as described in connection with the first form of the invention and is provided with pins, not shown, corresponding to the pins I3 so that it will lock beneath the spring arms I as described in connection with the first form of theinvention as shown in Figures 1 through 5. The lower portion of the structure is the same as that shown in Figure 1.

In the form of the invention shown in Figure 7, the fuse tube 36 is provided at its upper end with the upper terminal 31 which has an upper reduced neck portion 38 whose lower portion is threaded as indicated at 39. A nut 40 is screwed on the threaded portion of the neck and is provided with a slanting inner surface provided with a plurality of serrations which form ridges 4| extending longitudinally of the inner slanting surface of the nut 40.

The nut is adapted to clamp the upper button head or other shaped head 42 of the fuse link against the reduced neck of the upper terminal of the fuse tube as previously described, and it is apparent that the ridges 4| will bite to a limited extent into the marginal edges of the soft head 42 of the fuse link.

When the fuse link blows under heavy overload, sufficient gas pressure is generated as previously described to blow the head of the link outwardly through the nut. The ridges 4| cut into the soft metal of the head of the link as this soft metal will freely yield during its expulsion. The fuse tube is open at both ends as previously described and is supported at its lower end in the same manner as that described in connection with Figure 1. The upper terminal 31 of the fuse tube is constructed in the same manner as the upper terminal i2 of the fuse tube shown in Figure 1 and it is intended that such upper terminal shall be provided with outwardly projecting pins corresponding to the pins I3 of Figure 1 so that the device may be detachably locked to the upper contact in the same manner as that shown in Figure 1.

Instead of a regular series ofridges diametrically opposed ridges 43 may be provided as shown in Figure 9, the nut in such figure being indicated by the reference character 40'.

It will be seen that drop-out fuse devices have been provided in which provision is made for the normal operation of the devices as straight expulsion fuse constructions under light overload while at the same time providing for the free venting of the fuse tube at both ends under heavy overload.

Further it will be seen that the construction is relatively simple and does not add any material complication to the usual type of drop-out fuse device.

Although this invention has been described in considerable detail, it is to be understood that such description is intended as illustrative rather than limiting, as the invention may be variously embodied and is to be interpreted as claimed.

I claim:

1. In a fuse construction, stationary terminals, a fuse tube open at both ends and having a terminal at one end normally electrically connected to one of the stationary terminals, a fuse link extending through the fuse tube and electrically connecting' the other stationary terminal with the terminal of the fuse tube and having a head nora pair of mally closing one end of the fuse tube and in contact with the terminal of the fuse tube, and an annular member having a portion gripping the edges of the head of the fuse link and holding the head in tube closing position and in contact with the terminal of the fuse tube, whereby the head of the fuse link may be blown outwardly when suflicient pressure is developed in the fuse tube'upon rupture of the fuse link on heavy overload.

2. In a fuse construction, stationary terminals, a fuse tube open at both ends and having a terminal at one end normally electrically connected to one of the stationary terminals, a fuse link extending through the fuse tube and electrically connecting the other stationary terminal with the terminal of the fuse tube and having a head normally closing one end of the fuse tube and in contact with the terminal of the fuse tube, and an annular member screwed on the terminal of the fuse tube with the head of the fuse link engaging the mternal surface of the annular member and holding the head in tube closing position, whereby the head of the fuse link may be blown outwardly when sufficient pressure is developed in the fuse tube upon rupture of the fuse link.

3. In a fuse construction, stationary terminals, a fuse tube open at both ends and having a terminal at one end normally electrically connected to one of the stationary terminals, a fuse link extending through the fuse tube and electrically connecting the other stationary terminal with the terminal of the fuse tube and having a head normally closing one end of the fuse tube and in contact with the terminal of the fuse tube, and an annular member provided with a tapered internal aperture for the head of the fuse link, said annular. member being removably secured to the terminal of the fuse tube with the annular member gripping the head of the fuse link, whereby the head of the fuse link may be blown outwardly when suflicient pressure is developed in the fuse tube upon rupture of the fuse link on heavy overload.

4. In a fuse construction, stationary terminals, a fuse tube open at both ends and having a terminal at one end normally electrically connected to one of the stationary terminals, a fuse link extending through the fuse tube and electrically connecting the other stationary terminal with the terminal of the fuse tube and having a head normally closing one end of the fuse tube and in contact with the termir'nl of the fuse tube,

and an annular member provided with a tapered internal aperture for the head of the fuse link, said annular member being removably secured to the terminal of the fuse tube with the annular member gripping the head of the fuse link and holding the head of the fuse link in firm engagement with the terminal of the fuse tube, whereby the head of the fuse link may be blown outwardly when suificient pressure is developed in the fuse tube upon rupture of the fuse link on heavy overload.

5. In a fuse construction, stationary terminals, a fuse tube open at both ends and having a terminal at one end normally electrically connected to one of the stationary terminals, a fuse link extending through the fuse tubeand electrically connecting the other stationary terminal with the terminal of the fuse tube and having a head normally closing one end of the fuse tube and in contact with the terminal of the fuse tube, and a nut provided with a tapered internal aperture for the head of the fuse link, said nut being fuse tube and controlled screwed on the terminal of the fuse tube with the nut gripping the head of'the fuse link, whereby thehead of the fuse link may be blown outwardly when sufficient pressure is developed in i trically connecting the other stationary terminal with the terminal of the fuse tube and having a head normally closing one end of the fuse tube and in contact with the terminal of the fuse tube, and a nut provided with a tapered internal aperture for the head of the fuse link, said nut being screwed on the terminal of the fuse tube with the nut gripping the head of the fuse link and holding the head of the fuse link in firm en gagement with the terminal of the fuse tube, whereby the head of the fuse linkmay be blown outwardly when sufficient pressure is developed in the fuse tube upon rupture of the fuse link on heavy overload.

7. In a fuse construction, stationary terminals,

a fuse tube open at both ends and having a terminal at one end normally electrically connected to one of the stationary terminals, a fuse link extending through the fuse tube and electrically connecting the other stationary terminal with the terminal of the fuse tube and having a head normally closing one end of the fuse tube and in contact with the terminal of the fuse tube, the terminal of said fuse tube having an opening therein for the reception of the head of the fuse link, and a set screw extending transversely through a part of said terminal for temporarily holding the head of said fuse link in the terminal of said fuse tube, whereby'the head of the fuse link may be blown outwardly when suflicient pressure is developed in the fuse tube upon rupture of the fuse link on heavy overload.

8. In a drop-out fuse construction, an upper and a lower stationary terminal, a fuse tube open at both ends and having a terminal at its upper end, said upper stationary terminal having a pair of arms engaging'opposite sides of the upper terminal of said fuse tube and normally interlocking therewith, a fuse link extending through the fuse tube and electrically connecting the other stationary terminal with the terminal of the fuse tube and having a head normally closing one end of the fuse tube and normally in contact with the terminal of the fuse tube, a nut screwed on the terminal of the fuse tube and having a tapered aperture therethrough engaging the marginal edges of the head of the fuse link and holding the head of the fuse link in tube closed position, and a lever supporting the lower end of the by said fuse link and releasing said fuse tube for drop-out motion upon rupture of said fuse link, the arms of said upper stationary terminal engaging the terminal of the fuse tube at points spaced downwardly from the head of the fuse link. r v

9. In a fuse construction, stationary terminals, a fuse tube open at both ends and having a terminal at one end normally electrically connected to one of the stationary terminals, a fuse link extending through the fuse tube and electrically connecting the other stationary terminal with the terminal of the fuse tube and having a head normally closing one end of the fuse tube and normally in contact with the terminal of the fuse gripping force of tube, and a nut screwed on the terminal of the fuse tube and having a tapered aperture therethrough whose inner wall engages the marginal edge of the head of the fuse link and holds the head of the fuse link in tube closed position and in contact with the terminal of the fuse tube, the

said nut against the head of the fuse link maintaining said head in tube closed position upon light overload and allowing said head to be blown from said fuse tube under heavy overload, whereby upon light overload said fuse tube acts as an expulsion fuse tube and on heavy voverload said fuse tube is vented at both ends.

10. In a fuse construction, stationary terminals, a fuse tube open at both ends and having a terminal at one end normally electrically connected to one of the stationary terminals, a fuse link extending through the fuse tube and electri-- cally connecting the other stationary terminal with the terminal of the fuse tube and having a head normally closing one end of the fuse tube and in contact with the terr'ninal of the fuse tube,

the terminal of said fuse tube having an open-.

ing therethrough, the outer portion of said opening being of larger size and adapted to receive the head of said fuse link and the inner portion of said opening being of smaller size, and a set screw extending transversely of the terminal of said fuse tube and engaging the side of the head of said fuse link for temporarily clamping the head of said fuse link in place, whereby the head of the fuse link may be blown outwardly when sufficient pressure is developed in the fuse tube upon rupture of the fuse link on heavy overload.

11. In a drop-out fuse construction, an upper and a lower stationary terminal, a fuse tube open at both ends and having an upper terminal normally electrically connected to and interlocking with said upper stationary terminal, a fuse link extending through said fuse tube and normally electrically connecting the terminal of the fuse tube with the lower stationary terminal and having a head normally closing the upper end of the fuse tube and in contact with the upper terminal of said fuse tube, a nut having a tapered aperture therethrough for the head of the fuse link, said nut being screwed on the upper terminal of said fuse tube and gripping the head of the fuse link,said head being adapted to be blown outwardly through said nut on heavy overload, and

support means pivotally supporting said fuse tube adjacent its lower end, said support means being controlled by said fuse link and releasing said fuse tube upon rupture of said fuse link by lowering said fuse tube to allow the upper terminal of said fuse tube to detach itself from the upper stationary contact for drop-out motion of said fuse tube.

12. In a fuse nals, a fuse tube open at both ends and having a terminal at one end normally electrically connected to one of the stationary terminals, a fuse link extending through the fuse tube and electrically connecting the other stationary terminal with the terminal of the fuse tube and having a head normally closing one end of the fuse tube and in contact with the terminal of the fuse tube, and an annular member screwed on the terminal of the fuse tube with the head of the fuse link engaging the internal surface of the annular member and holding the head in tube closing position, the internal surface of the annular member being smooth, whereby the head of the fuse link may be blown outwardly when sumcient presconstruction, stationary termi- I the fuse tube; said fuse sure is developed in the fuse tube upon rupture of the fuse link.

13. In a fuse construction, stationary tenninals, a fuse tube open at both ends and having a terminal at one end normally electrically connected to one of the stationary terminals, a fuse link extending through the fuse tube and electrically connecting the other stationary terminal with the terminal of the fuse tube and having a head normally closing one end of the fuse tube and in contact with the terminal of the fuse tube, and having an annular member screwed on the terminal of the fuse tube withthe head of the fuse link engaging the internal surface of the annular member and holding the head in tube closing position, the internal surface of the annular member having at least two opposed ridges, whereby the head of the fuse link may be blown outwardly when sumcient pressure is developed in the fuse tube upon rupture of the fuse link.

14. In a fuse construction, stationary terminals, a fuse tube open at both ends and having a terminal at one end normally electrically connected to one of the stationary terminals, a fuse link extending through the fuse tube and electrically connecting the other stationary terminal with the terminal of the fuse tube and having a head normally closing one end of the fuse tube and in contact with the terminal of the fuse tube, and an annular member screwed on the terminal of the fuse tube with the head of the fuse link engaging the internal surface of the annular member and holding the head in tube closing position, the internal surface of the annular member being provided with a series of ridges extending lengthwise of the annular member, whereby the head of the fuse link may be blown outwardly when suiiicient pressure is developed in the fuse tube upon rupture of the fuse link.

15. In a fuse device a pair of stationary contacts, a fuse tube open at both ends, a fuse link electrically connecting said stationary contacts and having a head normally closing one end of the fuse tube, said fuse link extending from the head through the fuse tube and projecting out of the other end of the fuse tube, and means engaging the head of the fuse link and leaving an unobstructed path for discharge for the head of the fuse link upon rupture of the fuse link.

16. In a fuse device a pair of stationary contacts, a fuse tube open at both ends, a fuse link electrically connecting said stationary contacts and having a head normally closing one end of the the fuse tube, said fuselink extending from the head through the fuse tube and projecting out of the other end of the fuse tube, and means engaging the head of the fuse link independently of anypullonthefuselinkandleavinganun obstructed path for discharge for the head of the fuse link upon rupture of the fuse link.

17. In a fuse device a pair of stationary contacts, a fuse tube open at both ends. a fuse link electrically connecting said stationary contacts and having ahead normally closing one end of link extending from the head through the fuse tube and projecting out of the other end :of the fuse link, and means gripping thehead of the hiss link and leaving an unobstructed path for discharge for the head of the fuse link upon rupture of the fuse link under heavy overloads.

18. An expulsion fuse device comprising a fuse tube open at both ends, a fuse link having a head normally closing one end of the fuse tube and extending through the fuse tube and having a free end projecting out of the other open end of the fuse tube, means for securing the free end of the fuse link, and means for laterally engaging the head of the fuse link, whereby upon rupture .of the fuse link upon heavy overloads said head can move directly outwardly away from the end of the fuse tube, said head remaining in place upon rupture of the fuse link on light overloads.

19. A drop-out fuse device comprising a pair of spaced stationary contacts, a fuse tube open at both ends, a fuse link provided with a head closing one end of said fuse tube and extending through the fuse tube and electrically joining said stationary contacts, means controlled by said fuse link for releasably holding said fuse tube in operative position, and means carried by said fuse tube and laterally gripping the head of said fuse link.

20. In a drop-out fuse device a pair of stationary contacts, a fuse tube open at both ends, a fuse link electrically connecting saidstationary contacts and having a head normally closing one end of the fuse, tube, said fuse link extending from the head through the fusetube and pro-' jecting out of the other end of the fuse tube. means engaging the head of the fuse link and leaving an unobstructed path for discharge for the head of the fuse link upon rupture of the fuse link, and means controlled by said fuse link for releasably holding said fuse tube in operative position.

21. In "a drop-out fuse device a pair of sta tionary contacts, a fuse tube open at both ends, a fuse link electrically connecting said stationary contacts and having a head normally closing one end of the fuse tube, said fuse link extending from the head through the fuse tube and projecting out of the other end of the fuse tube, means engaging the head of the fuse link independently of any pull on the fuse link and leaving an unobstructed path for discharge for the head of the fuse link upon rupture of the fuse link, and means controlled by said fuse link and dependent upon the pull of said fuse link for normally holding the fuse tube in operative position, said last mentioned means releasing said fuse tube for motion to inoperative position upon rupture of said fuse link.

22. A drop-out expulsion fuse device comprising a pair of stationary contacts, a fuse tube open at both ends, a fuse link electrically connecting said stationary contacts and having a wardly away from the end of the fuse tube, and

means attached to said fuse for normally holding said fuse tube in opera ve position.

. EDWIN A. LINK. 

